Demagnetizer device using permanent magnets



Mar h 2 1964 J. F. ST. DENIS 3,126,502

' DEMAGNETIZER DEVICE USING PERMANENT MAGNETS Filed Nov. 14, 1960 INV R. jade v; Z 6' 6711's:

17- ar/vzxsz United States Patent 3,126,502 DEMAGNETIZER DEVICE USING PERMANENT MAGNETS Joseph Frederick St. Denis, 16136 Evergreen, East Detroit, Mich. Filed Nov. 14, 1960, Ser. No. 68,762 2 Claims. (Cl. 317-203) This invention relates to demagnetizers and particularly to a demagnetizer for eliminating the magnetic force from fabricated parts of magnetic material which have been magnetized as a result of the manufacturing processes to which they have been subjected.

In the manufacture of tools, dies and other parts of steel and other magnetic materials, it frequently occurs that the material being worked becomes, to some extent, magnetized. It is believed that the magnetizing of a magnetic material is the result of the orientation of the individual atoms of the material in a more or less uniform direction. The electrons of each atom move through a dielectric field and as a result thereof each atom sets up its own magnetic field. Normally, however, the atoms are arranged in a random manner and, thus, the magnetic field of all of the atoms neutralize one another and the part, as a whole, is not magnetized. The force and stability of an undesired magnetic field produced as a by-product of a metal cutting operation or the like is relatively low and it has been found that by subjecting the material to a stronger magnetic field of rapidly changing direction, the atoms may be reoriented in a random arrangement to demagnetize the material.

Accordingly, it is an object of the present invention to provide a device by means of which a material to be demagnetized may be subjected to a magnetic field of rapidly changing direction.

It is another object of the present invention to provide a device of the above character which may be manually operated and which eliminates the necessity for utilizing an electric current or an electrically operated mechanism.

It is another object of the present invention to provide a device of the above character utilizing permanent magnets and which is capable of producing a changing magnetic field of high strength for its size and weight.

It is still another object of the present invention to provide a device of the above character which is portable, which may be easily and inexpensively fabricated, which is substantially maintenance free and which is highly convenient to use.

These and other objects of the present invention will become apparent from the following detailed description taken in conjunction with the accompanying drawings wherein:

FIGURE 1 is an elevational view, with parts broken away, of a demagnetizer embodying the principles of the present invention; and

FIG. 2 is a sectional view of the structure illustrated in FIGURE 1, taken along the line 22 thereof.

Referring now to the drawings, FIGS. 1 and 2 illustrate a rotatable member which is supported for rotation by a supporting structure 12. The rotatable member 10 includes a body 14 which may be made from any suitable non-magnetic material, as, for example, a rigid plastic material, and which is molded about a shaft 16. A key 18 carried by the shaft projects into the material of the body 10 to prevent relative rotation between the body 14 and shaft 16. The shaft 16 projects above and below the body 14 and provides means by which the body 14 may be journaled for rotation about the axis of the shaft 3,126,502 Patented Mar. 24, 1964 ice.

16. Supported within the body 14 are a plurality of U- shaped magnets which, in the present embodiment, are illustrated as being three in number and consist of magnets 20, 22 and 24.

The plastic body is illustrated herein as being of a generally disk-shaped configuration and is formed with flat, circular spaced parallel top and bottom walls 26 and 28, respectively, which are interconnected by a circular cylindrical outer peripheral wall 30. The magnets 20, 22 and 24 are circularly arranged about the axis of rotation of the unit with their north and south poles in alternately disposed position. In addition, the magnets are equally spaced about the axis of rotation of the body and the bight portions of each magnet are disposed adjacent the shaft 16.

The supporting structure 12 is made from a nonmagnetic material, such as aluminum, and includes a circular base plate 32 having a central hub or journal portion 34 adapted to receive the lower end of the shaft 16. A thrust washer 36 rests on the base plate 32 above the hub 34 and directly engages the bottom surface 28 of the body.

14. A frame member 38, of inverted U-shape, is pro vided with a pair of apertured lug portions 38a at its opposite sides to receive screws 39 for attachment to the base plate 32. The frame member 38 is formed with a central hub 40 adapted to receive the upper end of the shaft 16. A pulley 42 is non-rotatably fixed on the shaft 16 above the hub 40 and is adapted to receive a driving belt 44. The body 14 may thus be driven in rotation by the belt 44 while supported between the hubs 34 and 40. The belt, in turn, may be driven by any suitable driving means, as, for example, a manually operated driving pulley or crank pulley (not shown). It will, of course, be appreciated that many other devices for manually rotating the shaft 16 could be readily provided, by means of which the body 14 can be rotated without the necessity of using an electric motor or the like.

The portion of the device illustrated in FIGURES l and 2 is such that the lines of force of the magnetic field of the rotatable member 10 flow from the north poles of each of the magnets 20, 22 and 24 arcuately outwardly to the two south poles on the opposite sides thereof. Thus, the direction of the magnetic field between successive adjacent pairs of poles is reversed and, as the body 10 is rotated, the material held opposite the ends of the poles will be subjected to a magnetic field of constantly changing direction.

While it will be apparent that the preferred embodiments herein illustrated are well calculated to fulfill the objects above stated, it will be appreciated that the invention is susceptible to modification, variation and change without departing from the proper scope or fair meaning of the subjoined claims.

What is claimed is:

1. A demagnetizer including a body, means for supporting said body for rotation about a given axis, a plurality of permanent U-shaped magnets carried by said body and arranged circularly about said axis with the poles thereof extending away from said axis, said magnets having the north and south poles thereof in alternately disposed arrangement, whereby an object held in juxtaposition to the ends of said poles will be subjected to a magnetic field of alternating direction upon rotation of said body.

2. A demagnetizer including a body, means for supporting said body for rotation about a given axis, a plurality of permanent U-shaped magnets carried by said body and disposed in equally spaced circular arrangement about References Cited in the file of this patent UNITED STATES PATENTS Whilton Dec. 24, 1889 Karasick Jan. 16, 1940 Cluwen et al Nov. 1, 1955 Kriss et al Sept. 18, 1956 

1. A DEMAGNETIZER INCLUDING A BODY, MEANS FOR SUPPORTING SAID BODY FOR ROTATION ABOUT A GIVEN AXIS, A PLURALITY OF PERMANENT U-SHAPED MAGNETS CARRIED BY SAID BODY AND ARRANGED CIRCULARLY ABOUT SAID AXIS WITH THE POLES THEREOF EXTENDING AWAY FROM SAID AXIS, SAID MAGNETS HAVING THE NORTH AND SOUTH POLES THEREOF IN ALTERNATELY DISPOSED ARRANGEMENT, WHEREBY AN OBJECT HELD IN JUXTAPOSITION TO THE ENDS OF SAID POLES WILL BE SUBJECTED TO A MAGNETIC FIELD OF ALTERNATING DIRECTION UPON ROTATION OF SAID BODY. 